1. Field of the Invention
The present invention relates to the serial transmission of data by modulation of a signal voltage on a connection contact of an integrated circuit. More specifically, the present invention relates to the sending of data via a connection contact to a circuit arrangement having a controller for the receiving of data by means of a modulated signal voltage.
2. Description of the Related Art
DE 198 19 265 C1 describes a process for the parametrizing of an integrated circuit arrangement as well as an integrated circuit arrangement for this purpose. A start is made here from an integrated circuit arrangement comprising substantially permanently wired and permanently connected components. Parameters for the operation of the circuit arrangement can be given by a parametrization. A signal voltage connection on which a signal voltage is applied serves for the inputting of the parameters. The actual parameters are modulated onto the signal voltage, during which a comparator connected in after the signal voltage connection checks the applied signal voltage to see whether it rises above a threshold value.
Moreover, housings with a great plurality of connection contacts in the form of so-called pins are generally known, which housings serve to receive integrated circuit components, among other things. The inclusion of a freely programmable digital processor with further components required for the operation of a processor in the housing is known. Customarily, two connection contacts of the housing serve to apply a supply voltage and a base voltage, two further connection contacts to apply an earth connection or zero voltage and an operating voltage and a plurality of further connection contacts serve to input or output data.
Such circuit arrangements and also other integrated circuit arrangements use for testing and checking purposes either signal connection contacts run out of the corresponding housing for parallel or serial testing, or use, to the extent that only a few connection contacts are present, a single-level modulation of the supply voltage according to DE 198 19 265 C1 and/or a single modulation of the current consumption.
In order to be able to carry out a rapid unidirectional serial and synchronous test of an integrated circuit arrangement, DE 10 2006 022 985 A1 describes a circuit arrangement with a serial test interface for controlling a test operating mode, with a freely programmable digital processor, with a housing for receiving the test interface and the processor, and with connection contacts for a data and/or signal exchange with external components and apparatuses, in which a modulated single voltage can be applied on one of the connection contacts for transferring data and/or a cycle using at least two controllable voltage levels. The exceeding and/or dropping below the two voltage levels can already be detected by at least two comparators.
In integrated circuit arrangements for very few contact pins or PINs, each extra PIN is relatively expensive. It is therefore important to make possible a fully synchronous bidirectional communication in circuit arrangements for test purposes of the circuit arrangements themselves via as small a number of contact pins as possible.
Compared to the earlier state of the art, DE 10 2006 022 985 A1 eliminates disadvantages in that the transmission of a cycle and additionally of data takes place from a higher-order apparatus to the structural component via a voltage supply. An independent cycle source in the integrated circuit arrangement can be eliminated for a test operating mode as long as it is tested. A cycle that is transmitted frequently into the integrated circuit arrangement is also already made possible here. However, this concerns only a unidirectional transmission of data and thus an intersection that is only unidirectionally voltage-modulating. For a transmission of data or, optionally also sensor data, in the actual operation from the integrated circuit arrangement to a higher-order apparatus either a current modulation, that is expensive to design, at the supply voltage connection or the use of an additional contact pin or PINs is necessary.
The invention has the problem of suggesting for the serial sending of data via a connection contact an improved circuit arrangement, an apparatus designed for communication with it and a process that is improved for this purpose which can also be used in integrated circuit arrangements with a reduced number of in particular only two connection contacts without loss of possible functionalities or capacities. In particular, a test operating mode should be improved in a circuit arrangement according to DE 10 2006 022 985 A1 in such a manner that two voltage contact pins in addition to a voltage supply also make possible a bidirectional data transfer with low construction cost at the same time.